1. Field of the Invention
The present invention relates generally to transfer mechanisms and methods for cylindrical articles, and more particularly to a synchronized transfer mechanism for moving newly formed cans from a forming ram to a work station, such as a trimmer.
2. Description of the Prior Art
Production of thin wall drawn and ironed metal cans involves drawing of a cup of the metal, which may be, for instance, steel or aluminum, into an elongated can configuration and then ironing by means of dies to produce very thin walls. As a result of this process, the upper portion of the can is open and of uneven length while the bottom portion of the can is closed with an integral bottom. The uneven upper portion must be trimmed to produce a can body of uniform height prior to further processing steps.
As a rule, the cans are ejected axially from the ram by, for instance, air pressure and/or stripper fingers and fed into a chute. The chute serves as an accumulation volume and the trimmer is conventionally operated in nonsynchronous fashion. However, since the walls of the can are thin and fragile, and since the height of the can varies, the newly formed cans are difficult to transport with chute arrangements. An example of a chute or hopper feed is shown in Gladfelter et al, U.S. Pat. No. 2,298,366 and Windstrup, U.S. Pat. No. 3,548,769. Once the can is presented to the processing station in, for instance, an in-feed chute, it is often necessary to synchronize the feed of the cans with the work station such as by the screw feed shown in Cvacho et al, U.S. Pat. No. 3,756,103.
Thus, the prior art generally accumulated the newly formed cans in chutes or hoppers and provided the work station with an independent, unsynchronize supply which had to be resynchronized with the machine. The shortcomings and drawbacks of this approach was recognized in Langewis, U.S. Pat. No. 3,864,995. Instead of utilizing an accumulation area between the can forming machine and work station, this more recent teaching utilized an indexing star-wheel conveyor which stops in a position aligned with the end of the forming ram, receives a newly formed can, and rapidly accelerates the can into a work station. However, at the high line speeds involved, the indexing of the star-wheel involves substantial acceleration and requires a relatively complex drive to synchronize the stopping and starting star-wheel with the motion of the forming ram.
While not entirely appropriate for the purposes of the instant invention, Spain, U.S. Pat. No. 828,865 discloses a feed mechanism in which articles are dropped radially into a vertical wheel mechanism in which a full circle enclosure opens and closes symmetrically to receive the falling articles.